The present invention relates to weather strips, and in particular, relates to weather strips having bulb portions fabricated from thermoplastic elastomeric materials.
Weather strips for residential and industrial windows and doors are fabricated in a variety of designs. One popular design includes a bulb sealing portion secured to a stem, where the stem is used to secure the bulb portion to a frame structure of the given window or door. This allows the bulb portion to function as a weather seal during use. The materials typically used for the stems and bulb portions desirably exhibit a variety of physical properties such as weatherability, sealability, ease of installation, low cost, and the like. However, many of the physical properties oppose each other. For example, a common bulb portion material includes ethylene propylene diene monomer (EPDM) rubber, which is a thermosetting material that provide good flexibility and sealability. The flexibility of the EPDM rubber allows the respective bulb portion to be used with frame structures having sharp corners (e.g., 90-degree corners). However, due to their thermosetting nature, EPDM rubbers are difficult to recycle, thereby increasing environmental waste concerns. Furthermore, such materials have limited durabilities to weathering conditions (e.g., in non-black colors), which can reduce the useful lives of the weather strips.
Other conventional weather strips have bulb portions with rigid walls to provide good weather seals. However, when negotiating around sharp corners, such weather strips typically bulge, pucker, and/or wrinkle, thereby reducing their ability to form proper weather seals at the given corners. One common technique for eliminating the bulging, puckering, and/or wrinkling at the sharp corners involves cutting the weather strips into segments at the corners. However, this technique leaves small gaps at the corners, which can allow air and water to flow through. Accordingly, there is an ongoing need for weather strips capable of forming good weather seals around sharp corners.